1. Field of the Invention
The present invention, in general relates to a system and method for injecting chemical grout and, more particularly, to grout injection devices that accept three grout components simultaneously.
The use of chemical grout injection devices are, in general, known. They typically disclose methods and apparatus useful for injecting either a pre-mixed grout, such as cement, or for injecting two grout components simultaneously so as to create a chemical reaction that produces grout in-situ. Chemical grouts that require the mixing of two components are referred to as "binary" grouts.
Chemical "additives" are sometimes used with binary grouts to modify some characteristic of the resultant grout, for example the time it takes for the grout to set or cure. If the additive hastens the time required to set, it is commonly known as an "accelerator". Usually, the additive is included as a mixture in solution with one of the two principle component parts before they are combined (and reacted together).
When grout is being injected into an area in which a pervasive flow of water exists, such as is found under or around water dams or through cracks in the dam structures, the water will be flowing at great volume and under great pressure. If the grout being used under such or similar circumstances were of a slow set (cure) time, the pervasive flow would simply carry the grout away as soon as it is injected, never being able to stop the flow or to seal the crack.
For a greater understanding of this problem and of certain prior solutions, U.S. Pat. No. 5,342,149 to McCabe et al, that issued Aug. 30, 1994, is useful and is herein incorporated as a reference.
An especially fast setting grout is required under such conditions. In particular, the binary grout components must be reacted so as to form an especially fast setting grout which is used to form an immediate barrier that can obstruct the pervasive flow. Accelerators are likely required to hasten setting time of even the fastest curing binary grouts.
Although the terminology is not elegant, a "glob" of especially fast setting grout must be formed as it is injected into a crack or crevice or fissure (each term is used interchangeably herein) in order to stop the flow. The grout must set-up and adhere to the surrounding structures before the pervasive flow can carry it away.
The necessity to inject an especially fast setting grout to seal a pervasive flow creates two inherent problems. A very fast setting grout, by definition, sets up quickly. Once set, it can no longer flow. As the cited McCabe prior patent reference addresses, it is not possible to react a very fast setting grout at the surface and then pipe it to a location to be grouted because it would "set" in the pipe and cease to flow. Therefore, it must be reacted in-situ. That is the purpose of having an injector. The first problem, then, is the need to react a fast setting grout in very close proximity to the crack or crevice to be filled with grout.
If a crack or crevice that is sealed is, in fact, sealed using only an especially fast setting grout, the crack or crevice will not be entirely filled by the grout. This is a second problem that is encountered when using an especially fast setting grout.
The tendency of the especially fast setting grout to form a "glob" does not stop once the pervasive flow is stopped but rather continues as more grout is injected into the crevice. Therefore, minute crevices are not adequately filled by the fast setting grout and voids can occur in even larger areas that are to be filled. Indeed, a series of adjoining "globs" can be formed that may provide a poor fill pattern.
Test core samples that may be drilled and extracted after to determine the quality of the grouting operation may contain excessive voids, possibly not satisfying predetermined specifications, and possibly even causing penalties to be incurred by the grouting contractor.
Indeed, the various "globs" may not completely stop the flow. A lesser volume of fluid (typically water) may find various paths around the "globs" and may continue to flow. This is worse than it seems. The mere fact that any flow might continue means that erosion will occur which, in time, can only exacerbate the problem.
The ideal solution is to vary the setting time of the resultant (reacted) grout during actual grouting operations. This has not been accomplished in the past because there has been no way to inject an additive, for example to hasten the set time to initially seal a pervasive flow and then gradually reduce or even eliminate the amount of additive that is being combined with the binary grout components as they are reacted.
Prior art has required that the fast setting grout be injected to seal the pervasive flow and then to either continue to seal the opening with the fast setting grout as best as can be accomplished or, alternatively, to stop the grouting process, readjust the grout mix by eliminating the additive from one of the two grout components (before they are reacted), and then to restart the grouting process anew.
To restart the process with a different grout "mix" results in a lack of continuity and a break in the integrity of the grout seal as the first "fast setting" grout will have set and created an interface (surface) against which the next round of grout must make contact. This can result in a path that can encourage additional or future leaks to occur as, for example, the water from a water dam eventually migrates under pressure to take advantage of the dissimilar grout interface. If the grouting process is continued with the fast setting grout, voids, as was described above, can form.
A monolithic pour (i.e., a continuous pour) is desirable to prevent a grout interface from being formed, yet no known way has heretofore been developed to do this that can actually vary the grout formulation and thereby vary the fill characteristics during the process of reacting and injecting grout, referred to herein as either injection or during the "pour".
One ideal solution, if it were possible, would be to allow varying the amount of additives that are used so as to initially provide a grout mix with an especially fast setting time to initially seal the crack enough to stop the pervasive flow, and to then vary the amount of additives "on the fly" so as to provide a grout mix with a slower setting time, but with better fill characteristics. If no cessation of grouting occurred, a monolithic pour having optimum fill characteristics would result.
As mentioned briefly above, prior types of two component grout injectors require that the desired additive be first mixed together with one of the two binary components. When a long hole is included, a great deal of pipe intermediate the surface and the old injector will be filled with the additive mixed together with one of the grout components. If the process is stopped and later restarted without the use of the additive, a great deal of wasted "mix" containing the additive results in one of the pipes as well as the need to reclaim the components during extraction of the injector. The risk of spillage at the surface also arises as is discussed in greater detail hereinafter.
A second ideal solution, if it were also possible, would be to vary the grout formulation (i.e., the type of grout provided by a manufacturer) that is being injected (used) without stopping the grout injection process.
For example, various types of binary urethane chemical grouts, aside from the additives that may be used with them, when reacted produce grouts that have different characteristics as is well known among those having ordinary skill in this art. Some grouts set more quickly than others (without the use of accelerators) because the setting time is an attribute of the particular formulation of grout that is being sold under any of various trade names. These various kinds of chemical grouts are available from the various manufacturers, again as is well known in the arts.
Some of these off-the-shelf grouts will adhere better to rock and cement formations while others will make a better bond with sediments, such as might be found under leaking water dams. Some are more flexible and can better tolerate movement of the structure such as might occur with further "settling" or shifting. This might happen in areas that are prone to earthquakes. Some off-the-shelf formulations produce a grout that is more rigid and may be useful for chemical grout applications where it is desirable to provide a grout having exceptional structural integrity. This may be especially useful in areas where the structure may be under load or may experience an increased load due to further settling or erosion.
Clearly, varying the type of grout that is used would also be especially useful as a method to improve the grouting operation. To do this most effectively, it is desirable to vary the grout formulation, again "on the fly" so as to produce a monolithic pour comprised of various grout formulations.
For example, to stop a pervasive flow injecting a fast setting grout formulation might be required to stop the flow followed by a shift to one having good flexibility and fill characteristics, but with a slower set time. Similarly a fast setting grout might be followed by a shift to one having the ability to permeate into the sediment or one that provides a more rigid grout formation. This order could, ideally, be reversed whenever it is desirable.
As is described in greater detail hereinbelow, the use of a tube-a-manchette" piping system may require the use of isolation packers for optimum results. The isolations packers isolate the various areas that are to be grouted and are themselves filled with grout. It is sometimes desirable to be able to fill one or more of the isolation packers with one particular grout formulation and to then inject a different type of grout formulation into the areas that are adjacent to the isolation packers.
Therefore, it is also desirable to be able to inject various grout formulations simultaneously (without having to extract the injector and piping) when using a tube-a-manchette piping system. This can improve efficiency and safety while also optimizing the grouting operation.
A way is needed to deliver any of three components through an injector and to be able to modulate in real time the introduction of those components at the injector. Ideally this control would take place at the surface where the workers are disposed. The three components can include the resin and the catalyst (usually water) and an additive, or if preferred another resin in place of the additive so as to provide an entirely different grout formulation.
If a fast setting grout were initially so injected, a change in pressure and delivery rate would alert an operator at the surface that the pervasive flow has been stopped or at least slowed down sufficiently so as to permit varying the amount of additive required or shifting from a fast setting grout to another type of grout to better satisfy the job requirements. Accordingly, the resultant grout could be varied to provide an optimum grout formulation and fill pattern for each site in exact accordance with the needs of that particular site. Some of the variables would be anticipated and initially set prior to the commencement of grouting, such as the general types of grout that are to be used and any additives that may be used. However, the actual variations in grouting must be able to occur as grout is being injected into the crack or crevice to produce a monolithic pour that is able to stop a pervasive flow and also provide an optimum formulation for the job at hand.
Also, there is another need as was mentioned briefly hereinabove that relates to injecting grout via a "sleeve-port" type of grout pipe that is also commonly referred to by the French term "tube-a-manchette". Sleeve-port grout pipes allow for the precise location and injection of grout at a predetermined depth along a plurality of spaced apart locations where there are "sleeve-ports" formed into the "tube-a-manchette" pipe for that purpose. However, these pipes which are small, typically 3 to 6 centimeters in diameter and more often two inches in diameter, do not readily accept larger types of grout injection devices.
Indeed, the standard prior art use of the "tube-a-manchette" system relies upon a simple pipe that is used to inject a pre-mixed grout directly into the crevice. The use of two pipes that are joined together in a "Y" configuration and which inject two grout components directly into a spiral mixer (to react them) is known generally, but not specifically for use with the tube-a-manchette piping system.
The prior art use with the tube-a-manchette includes a single pipe inserted into the tube-a-manchette and having a double packer, one packer disposed in front of and another disposed behind a pipe segment that includes holes (is ported) to allow discharge of the grout to occur. The prior art injection pipe is then inserted into the "tube-a-manchette" until the "ported" pipe segment portion aligns with the desired sleeve-port. See FIG. 15 for a diagram of the prior art.
Grout is pumped in through the injector pipe and out through grout holes or "ports" that are drilled through the wall of the "tube-a-manchette" pipe at predetermined spaced apart locations, wherever it is desirable to be able to inject grout. The ports are located at the sleeve-port locations.
The ports are each covered by a tightly fitting rubber sleeve that is disposed around the outside portion of the "tube-a-manchette" and which functions as a one-way check valve. The rubber sleeve, functioning as a one-way check valve, allows grout to be pumped out through the ports (grout holes) under pressure by pushing the rubber sleeve sufficiently far away from the "tube-a-manchette" so as to create a channel for the grout to exit from the grout holes.
The rubber sleeve, when grout is not being pumped out under pressure, forms a tight seal around the "tube-a-manchette" that prevents the entry of other objects or fluids into the "tube-a-manchette", such as water which may be present under pressure outside any of the ports.
The prior art injector pipe is inserted into the "tube-a-manchette" so as to align the end of the pipe with one of the sleeve-ports and grout is pumped down through the pipe and is injected.
A plurality of inflatable bags or collars are also typically inserted around the "tube-a-manchette" at spaced apart intervals, typically one every three to six meters, and are either inflated with a fluid to a predetermined pressure or they are filled with a grout, either cement or chemical grout, to provide a periodic seal and support structure surrounding the "tube-a-manchette" along its length. These inflatable bags are known as "isolation packers" and they divide the grout area into various areas.
The various areas that are formed allow for different grout formulations to be used as may be desired and also to water test, under pressure, the various areas before and after grouting to ensure that the grouting has in fact provided an effective seal.
One of the advantages of the tube-a-manchette system is that the tube-a-manchette pipe remains in the hole, because it is relatively inexpensive. A water test can then be performed by attempting to inject water in through any of the sleeve-ports and noting the resistance encountered by the pressure buildup that occurs. Water testing is accomplished by pumping water down through the pipe and out through one of the sleeve ports until a predetermined water pressure is attained at which water seepage is either not occurring or is less than a predetermined amount that is deemed as acceptable. This procedure can be used to verify that an effective grout seal has been formed in any of the areas intermediate any of the isolation packers.
In addition, the water test can thereafter be periodically performed to confirm the integrity of the grout seal. If any change has occurred which might warrant the injection of additional grout into any of the areas (between the isolation packers), the sleeve-ports in the tube-a-manchette can be used to regrout the areas. This provides a cost effective way to "maintain" a repair site.
If for example, future settling of a water dam foundation causes a previously grouted area to settle and to develop a fluid path (basically, a leak) that fails to hold pressure during the water test, it is possible to re-inject grout, perhaps a type of grout that flows easily, into the area thus "resealing" the area. Maintenance of the site is economically achieved.
It should be noted that if grout is injected under great pressure, it may be possible to fracture existing grout formations and conduct an additional supply of grout where it is needed. This is useful if the additional grout is needed some distance away from the tube-a-manchette.
During normal use of the tube-a-manchette system, grout is inserted into the injector pipe until that grouting operation is complete at a particular sleeve-port location (for a given area intermediate the isolation packers), at which time the injector pipe is moved (up or down) so as to align the injector portion with another sleeve-port location and the operation is repeated for the new area.
The "tube-a-manchette" allows for grout to be injected at any of the sleeve-port locations in any order, top to bottom or bottom to top and the ability to reapply grout at the same sleeve-port locations when desired. This makes the use of the tube-a-manchette piping system versatile.
However, the prior art, which does not rely upon the use of a valved injector with the tube-a-manchette pipe (for reasons as are discussed hereinabove) results in several problems. First, the use of especially fast setting grouts is limited because, if the grout is reacted at the surface, it will set in the pipe before it is injected.
Second, if two pipes were used in the tube-a-manchette and were joined together at the bottom with a "Y" adapter, and if a spiral mixer were then added, this would cause certain other problems to arise. This type of approach is known in the industry as "twin streaming" and is previously known for use in bore holes having a steel casing, but is not believed to be known for use with a tube-a-manchette pipe system.
If it were attempted with a tube-a-manchette, the grout would not be adequately reacted in the spiral mixer for reasons as are discussed in greater detail hereinbelow. Furthermore, the grout would tend to set-up and accumulate in and around the spiral mixer thus choking off the supply of grout and tending to seal the spiral mixer in position within the tube-a-manchette.
It may not be possible to extract the "Y" fitting, the double packer, and the spiral mixer from the tube-a-manchette pipe without it breaking off. If this occurs, future (maintenance) is rendered impossible. So too is the ability to grout, when it is advantageous to do so, from the top to the bottom of the tube-a-manchette.
As is well known in the arts, a temporary drill casing may be inserted into the bore-hole to provide stability under certain situations, into which the "tube-a-manchette" is inserted. Obviously, the temporary drill casing cannot block grout from escaping from the "tube-a-manchette", so it must be extracted from the bore hole prior to injecting grout.
The prior art "tube-a-manchette" approach requires the use of a small injector pipe that is inserted into the small "tube-a-manchette" pipe. The size (inner diameter) of the tube-a-manchette pipe is limited because the inflatable collars must, of necessity, be large than the "tube-a-manchette", or stated in another way, the "tube-a-manchette" must be smaller than the bore hole in order to accommodate the collars and, to a lesser extent, the rubber sleeves.
As was mentioned hereinabove for previous prior art tube-a-manchette applications, the injector pipe is a single pipe that is used to insert a single component grout. There is no room for known types of injectors which can both combine and mix (react) a binary type of a grout (two-component grout) in proximity to each sleeve-port and certainly no previously known way of using a three component injector under such space constraints.
Another problem inherent with known types of two-component grout injectors is that they may not adequately mix the grout components at the injection site, that is to say when the grout is reacted in-situ.
The reason for this is that known types of spiral, or "knife-edged" types of mixers mix by a process called inversion which results in a layering of the grout components by progressively dividing and recombining them in proportion to the number of elements of the mixer according to the power of 2. One element will result in one layer of the components being formed. Two elements will result in four layers total where the components are interlaced together. Three elements will result in eight layers that are interlaced together and so on.
As the space between the two packers of the "tube-a-manchette" and the spacing between the sleeve-ports each serve to limit the maximum possible length of any spiral type of a mixer that could be attached at the end of any conceivable two or more component grout injector, the number of elements are therefore limited and so too are the maximum number of layers formed also limited. The more layers formed, the greater the likelihood that the various components will adequately contact each other and be fully reacted.
Accordingly, there exists the likelihood that the grout will not be adequately layered and therefore it will not properly be mixed (reacted) prior to leaving the injector. If the injector is used with a "tube-a-manchette" piping system, the grout may not be fully reacted prior to leaving the "tube-a-manchette".
Not fully reacted grout components are worse than useless in that they take up space in the crevice without providing any additional strength or sealing characteristics. As such they impede the sealing of cracks and crevices that are to be grouted.
Therefore, there is a need to be able to react grout components better in two or three component types of injectors so that less reliance upon the spiral mixer is required. This need is especially acute for use with the "tube-a-manchette" piping system.
Also, the longer the spiral mixer must be, the greater the tendency is that the grout will begin to set up in the spiral mixer and cease to flow therefrom, thereby giving a false indication, by a rise in operating pressure, suggesting that the area has been sealed with grout when, in fact, the spiral mixer is clogged.
Also, the longer the spiral mixer is, the harder it is to clean or "flush" grout therefrom for use at the next station (sleeve-port location). Therefore, the fewer elements that are needed in the spiral mixer, the easier it becomes to clean and move the injector to another sleeve-port location and also the less likely it is that grout will clog the spiral mixer.
As time is a critical factor with fast setting chemical grouts, a spiral mixer begins to react some of the grout immediately as the first layering occurs. Subsequent grout may not be reacted and yet the first layers may begin to set and, as was mentioned hereinabove, to clog the spiral mixer.
Any application involving the use of binary chemical grouts requires that the grout components be reacted both quickly and in a short distance. These requirements create a need to effectively augment the reacting of chemical grouts by means other than reliance upon the spiral mixer. To make a spiral mixer more effective it must be longer with more elements but this, in turn, increases the time the grout will remain in the spiral mixer and it also increases the length of the mixer, both of which are limiting factors.
Another set of problems associated with grout injectors, in general, is that certain of the components of a binary grout system tend to be either expensive or hazardous, and they may be especially hazardous if they are reacted together at which time they may emit toxic gases and noxious fumes. Typically, as an injector is raised, certain sections of pipe that are full of these components must be disassembled, thus exposing workers to their effects as the components are spilled onto the work area. It is desirable to be able to fully recover certain of the components without spillage occurring, and especially without spillage of the primary components (typically the resin) so as to prevent any inadvertent reaction.
As water is usually the catalyst and is harmless if spilled, it is fine if water is spilled at the surface when an injector is withdrawn from a "deep hole". The additives and resins are what must be protected from spillage, not only for safety reasons, but also for reasons of economy.
Another problem associated with prior art chemical grout injectors, and especially when used with fast setting chemical grouts, is the tendency for the reacted grout to begin to accumulate within the injector body itself, thus restricting flow and impeding further grouting. Ideally, if turbulence is created within the injector body, not only are the grout components more fully reacted, and in a shorter period of time, but the turbulence also tends to keep the injector clean. Therefore, internal turbulence can be used to self-clean a chemical grout injector.
One further problem encountered when injecting grout into a long hole (deep hole) is that outside of the injector (or tube-a-manchette), water may be present under pressure. The injector must include valuing to restrict the entry of water into the injector body and up into the supply conduits (which supply resin or additives to the injector). Yet the valving must be able to overcome the outside "head" pressure level. Ideally, in order to create a predetermined release pressure for grout injection to occur, the valving should be adjustable so that release of the grout can occur at any desired pressure.
If for example, injecting the grout with one-hundred pounds per square inch of positive pressure produces optimum turbulence in the injector, optimum reacting of the grout components, and optimum grout distribution, the valving would need to open at one-hundred pounds per square inch pressure if there is zero head pressure outside of the injector.
If there is fifty pounds per square inch of head pressure, the valving would need to open when the grout component pressure to the injector is one-hundred and fifty pounds per square inch, thus yielding the proposed ideal working (or operating) pressure of one-hundred pounds per square inch.
Similarly, if the head pressure were one-hundred pounds per square inch, then the valving would, ideally, need to open at two-hundred pounds per square inch applied pressure. Indeed, the valving cannot begin to open until the head pressure, which tends to keep the valving (valves) closed, as is described in greater detail hereinafter, is itself exceeded. If the head pressure is one-hundred pounds per square inch, the valving will not be capable of opening until the interior pressure (in the injector) exceeds the head pressure.
As the head pressure can be measured prior to any injecting of the grout, it is possible to know what the ideal opening pressure must be before use in order to create the optimum working pressure. Valving that can be adjusted prior to use is therefore most desirable.
Accordingly there exists today a need for a three component grout injector that is small, helps to mix grout components together, which can be used with a "tube-a-manchette" piping system, and which is safer, more economical, and versatile to use.
Clearly, such an apparatus is an especially useful and desirable device.
2. Description of Prior Art
Grout injectors and grout injection systems are, in general, known. For example, the following patents describe various types of these devices:
U.S. Pat. No. 4,302,132 to Ogawa et al, November 1981;
U.S. Pat. No. 4,449,856 to Tokoro et al, May 1984;
U.S. Pat. No. 4,710,063 to Faktus et al, December, 1987;
U.S. Pat. No. 4,859,119 to Chida et al, August, 1989;
U.S. Pat. No. 5,006,017 to Yoshida et al, April, 1991;
U.S. Pat. No. 5,100,182 to Norkey et al, March 1992; and
U.S. Pat. No. to McCabe et al, August, 1994.
The following foreign patents are also known:
Japan patent 115,416 that issued September, 1981, and
United Kingdom patent 2,063,337 that issued June, 1981.
While the structural arrangements of the above described devices, at first appearance, have similarities with the present invention, they differ in material respects. These differences, which will be described in more detail hereinafter, are essential for the effective use of the invention and which admit of the advantages that are not available with the prior devices.